Induction chemotherapy followed by intensity-modulated radiotherapy with reduced gross tumor volume delineation for stage T3-4 nasopharyngeal carcinoma

Abstract

PurposeA common problem in stage T3–4 nasopharyngeal carcinoma (NPC) is the narrow gap between the primary tumor and neurological structures, which makes dose optimization difficult. Considering that significant tumor shrinkage may occur during induction chemotherapy (IC), this study explored the efficacy of intensity-modulated radiotherapy (IMRT) using reduced gross tumor volume (GTV) in the treatment of T3–4 NPC.Patients and methodsBetween January 2009 and April 2014, 103 patients with non-metastatic stage T3–4 NPC were prospectively recruited. They were assigned to accept IC, followed by reduced-volume IMRT and adjuvant chemotherapy. GTV was based on the post-IC volume of intracavity tumors and lymph nodes, and the pre-IC volume of the remaining involved structures.ResultsFor all treated patients, the 3-year local failure-free survival (LFFS) was 91.9%. After IC, 91 (88.3%) patients achieved local objective response (OR), and their 3-year LFFS rates were significantly better than in patients who failed to achieve local OR (94.1% vs 75.0%, P=0.023). A multivariate analysis demonstrated the prognostic value of tumor response to IC for LFFS. Dosimetric analysis showed good homogeneity, and the dose constraints were stringent. Asymptomatic temporal lobe necrosis in the ipsilateral side of tumor occurred in one patient.ConclusionIMRT using a reduced GTV delineation delivered satisfactory doses to the target volumes and avoided overdosing of critical neurological structures. Results showed satisfactory survival outcomes with few treatment-related toxicities. Tumor response to IC could facilitate selection of patients with stage T3–4 NPC eligible for treatment with this method.

Induction chemotherapy in the treatment of nasopharyngeal carcinoma: Clinical outcomes and patterns of care

“…The use of induction therapy in T4 and N3 is likely to reduce the target volumes for the definitive chemoradiation therapy. Studies have shown that use of induction therapy successfully reduces the target volumes of RT in order to avoid overdosing of critical neurological structures and reduce RT related toxicities 16, 17. For that reason, it is not surprising that we see higher use of induction therapy in these patients with very advanced disease.…”

Induction chemotherapy plus concurrent chemoradiotherapy versus induction chemotherapy plus volumetric modulated arc therapy alone in the treatment of stage II-IVB nasopharyngeal carcinoma patients: a retrospective controlled study

“…IMRT is able to escalate the dose to the target while sparing the adjacent critical structures [ 40 , 41 ], and has shown remarkable benefits in local control and relapse-free survival of NPC patients [ 31 , 42 , 43 ]. IMRT/VMAT has been widely applied clinically in the treatment of NPC.…”

Role of IMRT/VMAT-Based Dose and Volume Parameters in Predicting 5-Year Local Control and Survival in Nasopharyngeal Cancer Patients

“…Yang et al observed no significant differences in 1-, 2-, and 3-year OS, PFS, LRFFS, and DMFS with volume reduction after iCHT ( 29 ). Analogously, the experiences of Zhao et al ( 30 ) and Xue et al ( 31 ) reported good results in terms of disease control with mild toxicities. The dose–volume parameters to take into account in these situations are still to be defined and constitute an interesting field for future research.…”